Compressor system

ABSTRACT

A compressor system includes a compressor that includes an impeller configured to compress a working fluid by rotation. The compressor includes a housing in which an inflow flow path and a discharge flow path are formed, a guide vane that is provided in the inflow flow path and has an angle that is changeable, a diffuser vane that is provided in the discharge flow path and has an angle that is changeable, and a control unit configured to control angles of the guide vane and the diffuser vane. The control unit controls an angle of at least one of the guide vane and the diffuser vane based on a requested PQ characteristic value and a rotational speed of the impeller.

TECHNICAL FIELD

The present invention relates to a compressor system.

Priority is claimed on Japanese Patent Application No. 2015-054250,filed Mar. 18, 2015, the content of which is incorporated herein byreference.

BACKGROUND ART

A compressor system in which a motor and a compressor are integratedincludes a compressor configured to compress a gas such as air or thelike and a motor configured to drive the compressor. In the compressorsystem, a rotation shaft that extends from a casing of the compressorand a rotation shaft of a motor that similarly extends from a casing ofthe motor are connected. The rotation of the motor is transmitted to thecompressor. The rotation shafts of the motor and the compressor aresupported by a plurality of bearings and thus reliably rotate.

Such a compressor system is used for, for example, a subsea productionsystem as in Non Patent Literature 1 or a Floating Production Storageand Offloading (FPSO) unit as in Non Patent Literature 2. When thecompressor system is used for the subsea production system, thecompressor system is installed in the seabed. The compressor systemsends production fluids mixed with crude oils and natural gases that aredrawn from production wells drilled to a depth of several thousandmeters in the seabed to the sea surface. When the compressor system isused for the FPSO unit, the compressor system is installed in a marinefacility such as a ship.

CITATION LIST Non Patent Literature [Non Patent Literature 1]

Mitsubishi Heavy Industries Technical Review Vol. 34 No. 5 P310-P313

[Non Patent Literature 2]

Turbomachinery International September/October 2014 P18-P24

SUMMARY OF INVENTION Technical Problem

Incidentally, in a compressor system used for the subsea productionsystem and the FPSO unit, production fluids mixed with crude oils andnatural gases drawn from production wells in the seabed flow into thecompressor as fluids. There is a possibility of characteristics of theproduction fluids being changed due to a change of a content of oil ofcrude oil or the like during drawing. When characteristics of productionfluids change, the range in which the compressor can operate changes. Asa result, operation conditions of the compressor change.

The present invention provides a compressor system capable of respondingto changing operation conditions.

Solution to Problem

In order to address the above problems, the present invention proposesthe following solutions.

A compressor system according to a first aspect of the present inventionincludes a motor including a rotor configured to rotate about an axisand a stator that is disposed on an outer circumference side of therotor; and a compressor including an impeller that rotates together withthe rotor and compresses a working fluid, wherein the compressorincludes a housing in which an inflow flow path through which a workingfluid flows into the impeller and a discharge flow path through which aworking fluid pressure-fed by the impeller circulates are formed; aguide vane that is provided in the inflow flow path and has an anglethat is changeable; a diffuser vane that is provided in the dischargeflow path and has an angle that is changeable; and a control unitconfigured to control angles of the guide vane and the diffuser vane,and wherein the control unit controls an angle of at least one of theguide vane and the diffuser vane based on requested PQ characteristicvalues that are required pressure and flow rate values and a rotationalspeed of the impeller.

In such a configuration, it is possible to control an angle of at leastone of the guide vane and the diffuser vane based on the requested PQcharacteristic value and the rotational speed of the impeller.Therefore, it is possible to decrease at least one of an angle at whicha working fluid that flows into the impeller from the inflow flow pathflows and an angle at which a working fluid that flows into thedischarge flow path from the impeller flows. Therefore, a surge controlline can be changed to improve PQ characteristics during operation andit is possible to increase an operation range of the compressor.

In a compressor system according to a second aspect of the presentinvention, in the first aspect, when a rotational speed of the impelleris less than a predetermined reference, the control unit may control anangle of the guide vane so that a relative angle with respect to adirection in which the working fluid that flows into the impeller fromthe inflow flow path flows becomes smaller.

In such a configuration, when a rotational speed of the impeller is lessthan a predetermined reference, a relative angle of the guide vane withrespect to a direction in which a working fluid that flows into theimpeller from the inflow flow path which is a side in which a workingfluid flows into the impeller flows becomes smaller. Therefore, it ispossible to efficiently improve PQ characteristics. As a result, when anangle of the guide vane is adjusted, it is possible to efficientlyincrease an operation range of the compressor in a low pressure and lowflow rate area.

In a compressor system according to a third aspect of the presentinvention, in the first aspect, when a rotational speed of the impelleris greater than a predetermined reference, the control unit may controlan angle of the diffuser vane so that a relative angle with respect to adirection in which the working fluid that flows into the discharge flowpath from the impeller flows becomes smaller.

In such a configuration, when a rotational speed of the impeller isgreater than a predetermined reference, a relative angle of the diffuservane with respect to an angle at which a working fluid that flows intothe discharge flow path which is a side in which a working fluid fromthe impeller is discharged flows becomes smaller. Therefore, it ispossible to efficiently improve PQ characteristics. As a result, it ispossible to efficiently increase an operation range of the compressor ina high pressure and high flow rate area.

In a compressor system according to a fourth aspect of the presentinvention, in any one of the first to third aspects, when the requestedPQ characteristic value satisfies a requirement of a predeterminedreference, the control unit may control an angle of the guide vane sothat a relative angle with respect to a direction in which the workingfluid that flows into the impeller from the inflow flow path becomessmaller.

In such a configuration, it is possible to change an angle to improve PQcharacteristics only as necessary and it is possible to efficientlyincrease an operation range of the compressor.

In a compressor system according to a fifth aspect of the presentinvention, in any one of the first to third aspects, when the requestedPQ characteristic value satisfies a requirement of a predeterminedreference, the control unit may control an angle of the diffuser vane sothat a relative angle with respect to a direction in which the workingfluid that flows into the discharge flow path from the impeller flowsbecomes smaller.

In such a configuration, it is possible to change an angle to improve PQcharacteristics only as necessary and it is possible to efficientlyincrease an operation range of the compressor.

Advantageous Effects of Invention

According to the compressor system of the present invention, when anangle of at least one of the guide vane and the diffuser vane iscontrolled, it is possible to respond to changing operation conditionsby widening an operation range of the compressor.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram describing a compressor system accordingto an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an internal structure of acompressor according to an embodiment of the present invention.

FIG. 3 is a diagram of a relationship between a flow rate and a pressurein a compressor according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment according to the present invention will bedescribed with reference to FIG. 1 to FIG. 3.

A compressor system 1 is provided in the seabed for a subsea productionsystem that is one for ocean oil and gas field development methods andis provided on the sea surface for a Floating Production Storage andOffloading (FPSO) unit. The compressor system 1 pressure-feeds aproduction fluid such as oils and gases harvested from oil gas fieldproduction wells that are located several hundreds to thousands ofmeters from the seabed as a working fluid.

As shown in FIG. 1, the compressor system 1 includes a compressor 2, amotor 3, a bearing 4, a casing 5, and a control unit 6. The compressor 2includes a shaft 21 that extends in an O axis direction (in a horizontaldirection in FIG. 1) as a rotation shaft. The motor 3 includes a rotor31 that is directly connected to the shaft 21. The bearing 4 supportsthe shaft 21. The casing 5 accommodates the motor 3 and the compressor2. The control unit 6 controls the motor 3 and the compressor 2.

The compressor 2 is accommodated inside the casing 5. The compressor 2compresses a working fluid when the shaft 21 rotates about an O axistogether with the rotor 31. The compressor 2 of this embodiment includesthe shaft 21, an impeller 22, and the housing 23. The shaft 21 extendsin the O axis direction. The impeller 22 is fixed to an outercircumference surface of the shaft 21 and compresses a working fluid byrotating together with the rotor 31. The housing 23 covers the impeller22 from the outside.

The shaft 21 is a rotation shaft that extends in the O axis direction.The shaft 21 is supported by the casing 5 to be rotatable about the Oaxis. The shaft 21 passes through the housing 23 in the O axisdirection. The shaft 21 has ends both of which extend from the housing23. The shaft 21 extends in the O axis direction in the casing 5 to bedescribed below.

The impeller 22 rotates together with the shaft 21 and compresses aworking fluid that passes an impeller flow path 22 a formed therein togenerate a compressed fluid. A plurality of impellers 22 are fixed tothe outer circumference surface of the shaft 21 side by side with spacestherebetween in the O axis direction. Also, FIG. 1 shows an example inwhich the plurality of impellers 22 is provided. However, in thecompressor 2, at least one impeller 22 may be provided.

As shown in FIG. 2, through the impeller flow path 22 a, a working fluidis circulated from an inlet portion of the impeller 22 to an outletportion of the impeller 22. The inlet portion of the impeller 22 isformed at an end that faces an upstream side (the right side in FIG. 1and FIG. 2) that is one side of the impeller 22 in the O axis direction.The outlet portion of the impeller 22 is formed at an end that facesoutward in a radial direction with respect to the O axis of the impeller22.

The housing 23 is an exterior of the compressor 2. The housing 23accommodates the impeller 22 therein. The housing 23 is accommodatedinside the casing 5. In the housing 23, a plurality of internal spaces23 a whose diameters are repeatedly reduced and increased are provided.The impeller 22 is accommodated in the internal space 23 a. In theinternal space 23 a, the impeller 22 is disposed with a predeterminedspace between itself and the housing 23. In the housing 23, a housingflow path 24 is formed. Through the housing flow path 24, a workingfluid is circulated from the impeller 22 that is disposed on an upstreamside in the O axis direction to the impeller 22 adjacent on a downstreamside (the left side in FIG. 1 and FIG. 2) that is the other side in theO axis direction.

As shown in FIG. 2, the housing flow path 24 includes a suction flowpath 25, an intermediate flow path 26, and a discharge flow path (notshown). The suction flow path 25, through which a working fluid flowsinto the impeller 22 from the outside, is disposed on the furthestupstream side in the O axis direction. The intermediate flow path 26 isformed between the plurality of impellers 22. Through the discharge flowpath (not shown), a working fluid compressed by the impeller 22 disposedon the furthest downstream side in the O axis direction is discharged tothe outside.

The suction flow path 25 is formed at a position on the upstream siderelative to the impeller 22 that is disposed on the furthest upstreamside in the O axis direction. The suction flow path 25 is an inflow flowpath through which a working fluid flows into the impeller 22 disposedon the furthest upstream side in the O axis direction. The suction flowpath 25 extends inward in the radial direction from an opening formed ina circumferential direction on the upstream side in the O axis directionof the housing 23. Through the suction flow path 25, a working fluid iscirculated to an inlet of the impeller flow path 22 a. An inlet guidevane 251 (a guide vane) is provided in the suction flow path 25. Theinlet guide vane 251 changes a direction of a working fluid suctionedfrom the outside of the housing 23 to a desired direction and guides theworking fluid to the impeller flow path 22 a.

The inlet guide vane 251 has an angle that is changeable by an operatingmechanism (not shown). The desired direction in the inlet guide vane 251is, for example, a direction in which pre-rotation is applied to theworking fluid suctioned from the outside. The desired direction in theinlet guide vane 251 is, for example, a direction inclined toward thefront side of the impeller 22 in a rotation direction as it advances inthe radial direction. The inlet guide vane 251 of this embodiment has anangle that is adjusted based on a signal from the control unit 6 suchthat a relative angle with respect to a direction in which a workingfluid that flows into the impeller flow path 22 a flows becomes smaller.

The intermediate flow path 26 is formed to connect adjacent impellers 22in the O axis direction. The intermediate flow path 26 does notcommunicate with the outside of the housing 23 and is formed inside thehousing 23. The intermediate flow path 26 includes a diffuser flow path27 and a return flow path 28. The diffuser flow path 27 extends outwardin the radial direction from an outlet portion of the impeller flow path22 a. The return flow path 28 is connected to the diffuser flow path 27and extends to the inlet portion of the impeller flow path 22 a of theadjacent impeller 22.

The diffuser flow path 27 has an inlet that faces the outlet portion ofthe impeller flow path 22 a. Through the diffuser flow path 27, aworking fluid discharged from the impeller flow path 22 a is circulatedoutward in the radial direction. The diffuser flow path 27 is adischarge flow path through which a working fluid pressure-fed by theimpeller 22 circulates. In the diffuser flow path 27, a diffuser vane271 is provided. The diffuser vane 271 changes a direction of theworking fluid discharged from the impeller flow path 22 a to a desireddirection.

The diffuser vane 271 has an angle that is changeable by an operatingmechanism (not shown). The desired direction in the diffuser vane 271 isa direction in which a dynamic pressure of a circulating working fluidis restored as a static pressure. The desired direction in the diffuservane 271 is a direction inclined toward the front side of the impeller22 in a rotation direction as it advances in the radial direction. Thediffuser vane 271 of this embodiment has an angle that is adjusted basedon a signal from the control unit 6 such that a relative angle withrespect to a direction in which a working fluid that flows into thediffuser flow path 27 from the impeller flow path 22 a flows becomessmaller.

The return flow path 28 is an inflow flow path through which a workingfluid that has circulated in the diffuser flow path 27 flows into theimpeller flow path 22 a. The return flow path 28 includes a curved flowpath 281 and a linear flow path 282. The curved flow path 281 isconnected to an outer end of the diffuser flow path 27 in the radialdirection. The linear flow path 282 is connected to an end of the curvedflow path 281.

The curved flow path 281 is continuously formed with respect to theoutside of the diffuser flow path 27 in the radial direction. The curvedflow path 281 extends outward in the radial direction and then curvesinward in the radial direction. In the curved flow path 281, a flow ofthe working fluid that moves outward in the radial direction is changedto a flow that moves inward in the radial direction.

The linear flow path 282 extends inward in the radial direction from thecurved flow path 281 to an inlet portion of the impeller flow path 22 a.The linear flow path 282 is continuously formed with respect to a sideopposite to a portion connected to the diffuser flow path 27 of thecurved flow path 281. In the linear flow path 282, a return vane 282 athat changes a direction of a working fluid that has circulated in thediffuser flow path 27 to a desired direction is provided.

As shown in FIG. 1, the motor 3 is accommodated in the casing 5 with aspace in the O axis direction between itself and the compressor 2. Themotor 3 includes a rotor 31 and a stator 32. The rotor 31 is fixed to beintegrated with the shaft 21. The stator 32 is disposed on an outercircumference side of the rotor 31.

The rotor 31 is integrated with the shaft 21 and rotatable about the Oaxis. The rotor 31 is directly connected to an outer circumference sideof the shaft 21, which is the outside in a circumferential directionwith respect to the O axis so that it integrally rotates with the shaft21 of the compressor 2 without intervening of gears and the like. Therotor 31 includes, for example, a rotor core (not shown) in which aninduced current flows when the stator 32 generates a rotating magneticfield.

A gap in the circumferential direction is provided between the stator 32and the rotor 31 to cover the rotor 31 from the outer circumferenceside. The stator 32 includes a plurality of stator cores (not shown)that are disposed in, for example, the circumferential direction of therotor 31, and a stator winding (not shown) wound on the stator core.When a current flows from the outside, the stator 32 generates arotating magnetic field and rotates the rotor 31. The stator 32 is fixedinto the casing 5.

The bearing 4 is accommodated inside the casing 5 and rotatably supportsthe shaft 21. The bearing 4 of this embodiment includes a plurality ofjournal bearings 41 and thrust bearings 42.

The journal bearing 41 supports a load on the shaft 21 in the radialdirection. Journal bearings 41 are disposed at both ends of the shaft 21in the O axis direction to sandwich the motor 3 and the compressor 2 inthe O axis direction. The journal bearing 41 is also disposed between anarea in which the compressor 2 is provided and an area in which themotor 3 is provided, which is on the motor 3 side relative to a sealingmember 51 to be described below.

The thrust bearing 42 supports a load on the shaft 21 in the O axisdirection through a thrust collar 21 a that is formed at the shaft 21.The thrust bearing 42 is disposed between the area in which thecompressor 2 is provided and the area in which the motor 3 is providedand is on the compressor 2 side relative to the sealing member 51 to bedescribed below.

The casing 5 accommodates the compressor 2 and the motor 3 therein. Thecasing 5 has a cylindrical shape along the O axis. An inner surface ofthe casing 5 protrudes toward the shaft 21 between the compressor 2 andthe motor 3 in the O axis direction. The casing 5 is provided on aportion from which the sealing member 51 sealing a gap between the areain which the compressor 2 is provided and the area in which the motor 3is provided protrudes.

The control unit 6 controls the compressor 2 and the motor 3 so that thecompressor 2 is operated according to predetermined operationconditions. The control unit 6 controls angles of the inlet guide vane251 and the diffuser vane 271. The control unit 6 controls therotational speed of the rotor 31 of the motor 3. As shown in FIG. 2, thecontrol unit 6 includes an input unit 61, a determination unit 62, andan output unit 63. In the input unit 61, a requested PQ characteristicvalue that is a requested pressure and flow rate value and a requestedrotational speed that is a requested rotational speed of the impeller 22are input. The determination unit 62 determines whether the inputrequested PQ characteristic value and the requested rotational speedsatisfy requirements of predetermined references. The output unit 63sends a signal to the motor 3, the inlet guide vane 251, and thediffuser vane 271 based on the determination result of the determinationunit 62.

The input unit 61 outputs the input requested PQ characteristic valueand requested rotational speed to the determination unit 62.

The determination unit 62 determines whether the requested rotationalspeed satisfies a requirement of a predetermined reference anddetermines whether the requested PQ characteristic value is within aninitial operation range. The determination unit 62 sends an instructionto the output unit 63 of an extent to which to adjust an angle of theinlet guide vane 251 or the diffuser vane 271 based on the determinationresult.

Here, the initial operation range is a range in which the compressor 2in an initial setting state can operate without causing a surge. Incurves showing a relationship between a pressure and a flow rate of thecompressor 2 shown in FIG. 3, the initial operation range indicates anarea on the right side relative to surge control lines SCL 11 and SCL 12and surge control lines SCL 21 and SCL 22. The surge control lines SCL11 and SCL 12 are determined by the inlet guide vane 251 and thediffuser vane 271 whose angles are set to initial values. The surgecontrol lines SCL 21 and SCL 22 are determined by the inlet guide vane251 and the diffuser vane 271 after angles are changed, which will bedescribed below. Also, in an area on the left side relative to suchsurge control lines, surge occurs.

Specifically, the determination unit 62 of this embodiment determineswhether the input requested rotational speed is less than apredetermined first reference. The determination unit 62 determineswhether the input requested rotational speed is greater than apredetermined second reference.

Here, the first reference refers to a rotational speed at which thecompressor 2 operates in an area in which a pressure and a flow rate arelower than those in a state at 100% of the rotational speed when arotational speed during a rated operation is set to 100%. On the otherhand, the second reference refers to a rotational speed at which thecompressor 2 operates in an area in which a pressure and a flow rate arehigher than those in a state at 100% of the rotational speed.

In this embodiment, the first reference is set to 100% of the rotationalspeed. In this embodiment, the second reference is set to 110% of therotational speed.

When the input requested rotational speed is less than 100% of therotational speed serving as the first reference, the determination unit62 sends an instruction to the output unit 63 to adjust the inlet guidevane 251. When it is determined that the requested rotational speed isless than the first reference, the determination unit 62 determineswhether the input requested PQ characteristic value is within an area onthe right side relative to the low side surge control line SCL 12 of anarea having a low pressure and a low flow rate in the initial operationrange. Therefore, for example, when the requested PQ characteristicvalue is a value of an area α in FIG. 3, it is determined that therequested PQ characteristic value exceeds the low side surge controlline SCL 12. In this case, the determination unit 62 sends aninstruction to the output unit 63 to adjust an angle of the inlet guidevane 251 so that a relative angle with respect to a direction in which aworking fluid that flows into the impeller flow path 22 a from thesuction flow path 25 flows becomes smaller.

When the input requested rotational speed is greater than 110% of therotational speed serving as the second reference, the determination unit62 sends an instruction to the output unit 63 to adjust the diffuservane 271. When it is determined that the requested rotational speed isgreater than the second reference, the determination unit 62 determineswhether the input requested PQ characteristic value is within an area onthe right side relative to the high side surge control line SCL 11 of anarea having a high pressure and a high flow rate in the initialoperation range. Therefore, for example, when the requested PQcharacteristic value is a value of an area 13 in FIG. 3, it isdetermined that the requested PQ characteristic value exceeds the highside surge control line SCL 11. In this case, the determination unit 62sends an instruction to the output unit 63 to adjust an angle of thediffuser vane 271 so that a relative angle with respect to a directionin which a working fluid that flows into the diffuser flow path 27 fromthe impeller flow path 22 a flows becomes smaller.

When the input requested rotational speed is greater than the firstreference and less than the second reference, the determination unit 62sends an instruction to the output unit 63 not to adjust an angle of theinlet guide vane 251 or the diffuser vane 271. When the input requestedPQ characteristic value does not exceed the initial operation range, thedetermination unit 62 sends an instruction to the output unit 63 not toadjust an angle of the inlet guide vane 251 or the diffuser vane 271.

Based on the requested rotational speed input from the input unit 61through the determination unit 62, the output unit 63 sends aninstruction to the motor 3 to change a rotational speed of the rotor 31.Based on the determination result of the determination unit 62, theoutput unit 63 sends an instruction to the inlet guide vane 251 or thediffuser vane 271 to change an angle. Also, an amount of change in theangle of the inlet guide vane 251 or the diffuser vane 271 may beappropriately set based on a difference between the requested PQcharacteristic value and a current PQ characteristic value.

In this embodiment, when the instruction from the output unit 63 isreceived, an angle of the inlet guide vane 251 is adjusted. Therefore,as shown in FIG. 3, a position of the low side surge control line SCL 12in a low pressure and low flow rate area is changed to that of SCL 22.When the instruction from the output unit 63 is received, an angle ofthe diffuser vane 271 is adjusted. Therefore, a position of the highside surge control line SCL 11 in a high pressure and high flow ratearea is changed to that of SCL 12.

According to the compressor system 1 described above, based on therequested PQ characteristic value and requested rotational speed inputto the input unit 61 of the control unit 6, a current is supplied to thestator 32 by an external device such as a generator (not shown). Arotating magnetic field is generated based on the supplied current, andthe rotor 31 of the motor 3 starts rotating together with the shaft 21at the requested rotational speed. When the shaft 21 rotates at a highspeed, in the compressor 2, a working fluid that flows into thecompressor 2 from the upstream side in the O axis direction iscompressed by the impeller 22 that rotates together with the shaft 21,and a compressed fluid for which the requested PQ characteristic valueis satisfied is discharged from the downstream side in the O axisdirection.

Here, for example, when a quantity of state of a content of oil in aproduction fluid while the compressor system 1 operates varies,characteristics of the working fluid that flows into the compressor 2change and a discharge pressure of the compressor 2 changes. Therefore,the requested PQ characteristic value and the requested rotational speedare input to the input unit 61 of the control unit 6 such that aconstant discharge pressure of the compressor 2 is maintained. When therequested PQ characteristic value and the requested rotational speed areinput, the output unit 63 sends an instruction to the motor 3 to changea rotational speed of the rotor 31 according to the requested rotationalspeed. As a result, a rotational speed of the impeller 22 is adjustedthrough the rotor 31. At the same time, in the determination unit 62,when it is determined that the requested rotational speed is less thanthe first reference, it is determined whether the requested PQcharacteristic value exceeds the low side surge control line SCL 12.When the requested rotational speed is less than the first reference andthe requested PQ characteristic value exceeds the low side surge controlline SCL 12, the determination unit 62 sends a signal to the output unit63 to adjust an angle of the inlet guide vane 251. The inlet guide vane251 that has received the signal from the output unit 63 adjusts anangle such that a relative angle with respect to a direction in which aworking fluid that flows into the impeller flow path 22 a from thesuction flow path 25 flows becomes smaller. When an angle of the inletguide vane 251 is changed, a position of the low side surge control lineSCL 12 is changed to that of SCL 22. At the same time, an operation areaof 110% of the rotational speed is changed from a line L111 to a lineL112. Therefore, it is possible to improve PQ characteristics in a lowpressure and low flow rate area.

When it is determined that the requested rotational speed is greaterthan the second reference, the determination unit 62 determines whetherthe requested PQ characteristic value exceeds the high side surgecontrol line SCL 11. When the requested rotational speed is greater thanthe second reference and the requested PQ characteristic value exceedsthe high side surge control line SCL 11, the determination unit 62 sendsa signal to the output unit 63 to adjust an angle of the diffuser vane271. The diffuser vane 271 that has received the signal from the outputunit 63 adjusts an angle such that a relative angle with respect to adirection in which a working fluid that flows into the diffuser flowpath 27 from the impeller flow path 22 a flows becomes smaller. When anangle of the diffuser vane 271 is changed, a position of the high sidesurge control line SCL 11 is changed to that of the SCL 12. At the sametime, an operation area of 110% of the rotational speed is changed fromthe line L111 to the line L112. Therefore, it is possible to improve PQcharacteristics in a high pressure and high flow rate area.

That is, a surge control line can be changed to improve PQcharacteristics during operation. Therefore, even if a quantity of stateof a working fluid that flows in the impeller flow path 22 a is changed,it is possible for the compressor 2 to perform an operation for settinga discharge pressure to be constant over a wide range. Accordingly, itis possible to respond to changing operation conditions by widening anoperation range of the compressor 2.

When the requested rotational speed is low, the impeller 22 rotates at alow rotational speed. Therefore, the compressor 2 operates in a lowpressure and low flow rate area. That is, when the requested rotationalspeed is low, efficiency of compression of a working fluid by theimpeller 22 is low. Therefore, a volumetric flow rate of the workingfluid that circulates in the impeller flow path 22 a increases.Therefore, when the requested rotational speed is low, a direction inwhich a working fluid that flows in the impeller flow path 22 a flowsgreatly influences an operation range of the compressor 2. Therefore,when the requested rotational speed is less than the predetermined firstreference, a relative angle of the inlet guide vane 251 with respect toa direction in which a working fluid that flows into the impeller flowpath 22 a from the suction flow path 25 which is a side in which aworking fluid flows into the impeller flow path 22 a flows becomessmaller. Therefore, it is possible to efficiently improve PQcharacteristics. That is, when an angle of the inlet guide vane 251 isadjusted, it is possible to increase an operation range of thecompressor 2 more efficiently than when the diffuser vane 271 isadjusted in a low pressure and low flow rate area.

When the requested rotational speed is high, the compressor 2 operatesin a high pressure and high flow rate area. That is, when the requestedrotational speed is high, efficiency of compression of the working fluidis high. Therefore, a volumetric flow rate of a working fluid thatcirculates in the impeller flow path 22 a becomes smaller. Therefore, ina high pressure and high flow rate area, an angle at which a workingfluid discharged from the impeller flow path 22 a flows into thediffuser flow path 27 greatly influences an operation range of thecompressor 2. Therefore, when the requested rotational speed is greaterthan the predetermined second reference, a relative angle of thediffuser vane 271 with respect to an angle at which a working fluid thatflows into the diffuser flow path 27 which is a discharge side of aworking fluid from the impeller flow path 22 a flows becomes smaller.Therefore, it is possible to efficiently improve PQ characteristics.That is, when an angle of the diffuser vane 271 is adjusted, it ispossible to increase an operation range of the compressor 2 moreefficiently than when the inlet guide vane 251 is adjusted in a highpressure and high flow rate area.

Angles of the inlet guide vane 251 and the diffuser vane 271 aredetermined only when the requested PQ characteristic value exceeds theinitial operation range. Therefore, it is possible to change an angle toimprove PQ characteristics only as necessary and it is possible toefficiently increase an operation range of the compressor 2.

The embodiments of the present invention have been described in detailabove with reference to the drawings, but configurations andcombinations thereof in the embodiments are only examples, andadditions, omissions, substitutions and other modifications of theconfigurations can be made without departing from the scope of thepresent invention. In addition, the present invention is not limited tothe embodiments and is only limited by the scope of the appended claims.

Note that the guide vane is not limited to the inlet guide vane 251 thatis provided in the suction flow path 25 as in this embodiment. Any guidevane that is provided in the inflow flow path and can change a directionof a working fluid that flows in the impeller flow path 22 a to adesired direction may be used. For example, the guide vane may be thereturn vane 282 a that is provided in the linear flow path 282 of thereturn flow path 28.

While a configuration in which the inlet guide vane 251 serving as aguide vane and the diffuser vane 271 are disposed together is used inthis embodiment, the present invention is not limited to such aconfiguration. That is, in the compressor 2, only the guide vane may beprovided or only the diffuser vane 271 may be provided.

When the plurality of impellers 22 are provided, the guide vane and thediffuser vane 271 are not necessarily provided in all of the impellers22. The guide vane and the diffuser vane 271 may be disposed only aroundthe impeller 22 of a stage for which an operation range is to beadjusted.

In the determination unit 62 of this embodiment, as a reference fordetermining whether a value is within a predetermined operation range,the first reference and the second reference that are different fromeach other are used, and the present invention is not limited thereto.For example, one reference may be used to determine whether a value iswithin the predetermined operation range.

INDUSTRIAL APPLICABILITY

According to the above compressor system, when an angle of at least oneof the guide vane and the diffuser vane is controlled, it is possible torespond to changing operation conditions by widening an operation rangeof the compressor.

REFERENCE SIGNS LIST

1 Compressor system

O Axis

2 Compressor

21 Shaft

22 Impeller

22 a Impeller flow path

23 Housing

23 a Internal space

24 Housing flow path

25 Suction flow path

251 Inlet guide vane

26 Intermediate flow path

27 Diffuser flow path

271 Diffuser vane

28 Return flow path

281 Curved flow path

282 Linear flow path

282 a Return vane

3 Motor

31 Rotor

32 Stator

33 Gap

4 Bearing

41 Journal bearing

42 Thrust bearing

5 Casing

51 Sealing member

6 Control unit

61 Input unit

62 Determination unit

63 Output unit

1. A compressor system comprising: a motor including a rotor configured to rotate about an axis and a stator disposed on an outer circumference side of the rotor; and a compressor including an impeller rotating together with the rotor and compressing a working fluid, wherein the compressor includes a housing in which an inflow flow path through which a working fluid flows into the impeller and a discharge flow path through which a working fluid pressure-fed by the impeller circulates are formed; a guide vane provided in the inflow flow path and having an angle that is changeable; a diffuser vane provided in the discharge flow path and having an angle that is changeable; and a control unit configured to control angles of the guide vane and the diffuser vane, and wherein the control unit controls an angle of the guide vane based on a requested PQ characteristic value that is a requested pressure and flow rate value and a rotational speed of the impeller.
 2. The compressor system according to claim 1, wherein, when a rotational speed of the impeller is less than a predetermined reference, the control unit controls an angle of the guide vane so that a relative angle with respect to a direction in which the working fluid flowing into the impeller from the inflow flow path flows becomes smaller.
 3. (canceled)
 4. The compressor system according to claim 1, wherein, when the requested PQ characteristic value satisfies a requirement of a predetermined reference, the control unit controls an angle of the guide vane so that a relative angle with respect to a direction in which the working fluid flowing into the impeller from the inflow flow path flows becomes smaller.
 5. (canceled)
 6. A compressor system comprising: a motor including a rotor configured to rotate about an axis and a stator disposed on an outer circumference side of the rotor; and a compressor including an impeller rotating together with the rotor and compressing a working fluid, wherein the compressor includes a housing in which an inflow flow path through which a working fluid flows into the impeller and a discharge flow path through which a working fluid pressure-fed by the impeller circulates are formed; a guide vane provided in the inflow flow path and having an angle that is changeable; a diffuser vane provided in the discharge flow path and having an angle that is changeable; and a control unit configured to control angles of the guide vane and the diffuser vane, and wherein the control unit controls an angle of at least one of the guide vane and the diffuser vane based on a requested PQ characteristic value that is a requested pressure and flow rate value and a rotational speed of the impeller, and wherein, when a rotational speed of the impeller is less than a predetermined reference, the control unit controls an angle of the guide vane so that a relative angle with respect to a direction in which the working fluid flowing into the impeller from the inflow flow path flows becomes smaller. 